The elder brother of Raiko, 美女丸 Bijomaru,
took the sword and became quite wild. His father 源光仲 Mitsunaka ordered 藤原仲光 Fujiwara no Nakamitsu to kill Bijomaru, but Nakamitsu killed his own son instead and presented it to Bijomaru. Bijomaru finally changed his wild ways and became a monk at 比叡山 Hieizan.

- quote - 美女丸 Bijomaru and 幸寿丸 Kojumaru (小童寺 Shodoji Temple)
There is a tragic tale told of Shodoji Temple located in Nishiuneno.
Minamoto-no-Mitsunaka, who was the Lord of Settsu and the person who built Tada-In （Tada Shrine） in the 10th century, sent his son, Bijomaru, to Nakayamadera Temple （Takarazuka City, to receive training to become a Buddhist priest. Bijomaru, however, spent all his time playing martial arts, and was not serious at all in his training to become a priest.
One day, when Bijomaru became 15 years old, his father, Mitsunaka asked him how much progress he made in his training. When Mitsunaka realized that Bijomaru could not read Buddhist scriptures, nor compose a tanka （a 31-syllable Japanese poem） nor play music, he became furious and ordered his chief vassal, Nakamitsu Fujiwara, to kill Bijomaru by cutting his head.
Nakamitsu was in big difficulties, since he could not take the life of a son of his lord.
As Kojumaru, one of the sons of Nakamitsu, knew the plight of his father, he told his father to kill him instead. Nakamitsu found Kojumaru join his hands in prayer, and close his eyes. Holding back his tears, Nakamitsu slew his son, and let Bijomaru secretly go off to Mount Hiei （Shiga Prefecture）.
Bijomaru later found out what had happened, and devoted himself to ascetic practices to become a priest. He became a high-ranking priest, called Genken-sozu, and built Shodoji Temple to enshrine the spirit of Kojumaru.
The temple of this legend is highlighted by ever-changing scenery of the seasons, from cherry blossoms in spring to vibrant yellows and reds in autumn. - source : city.kawanishi.hyogo.jp -

- A friend remarked:... about Minamoto no Yorimitsu (raiko) and his father Mitsunaka ...
... until 1068 this family was 摂関 Sekkan (Sesshō+Kampaku), after it was Go-Sanjō-tennō (71th) and they took back the dictature until 1185
- anyway it means they were the highest level in the hierarchy
and the Minamoto-shi was Chinjufu-shōgun (so kokushi) meaning vassal of all the people of Fujiwara-shi.
So as the nippon-no-rekishi is very complex, this story is tricky, as a Fujiwara cannot be in the service of a Minamoto.
Any answers to this?

Niigata, 松之山町 Matsunoyama
The serpent wanted the princess of the pond 蒲生池 / 蒲生の池 Kamo-no-ike as his bride. But the Nakodo was refused. In his anger he killed all the members of the family.
He borrowed the famous serpent-cutting sword Hebikirimaru 蛇切丸 and fought with the enemy.

The sword Kimaru, Onimaru 鬼丸 used to kill the Tsuchigumo monster 土蜘蛛退治.
This sword is also called Hizamaru (膝丸)

- quote -
There are various theories to the story of the tsuchigumo, and in the Heike Monogatari, there is as following (they were written as 山蜘蛛).
When Yorimitsu suffered from malaria, and lay on a bed, a strange monk who was 7 shaku (about 2.1 meters) tall appeared, released some rope, and tried to capture him. Yorimitsu, despite his sickness, cut him with his famous sword, the Hizamaru (膝丸), causing the monk to flee. The next day, Yorimitsu led his Four Guardian Kings to chase after the blood trail of the monk, and arrived at a mound behind shrine Kitano jinja where there was a large spider that was 4 shaku wide (about 1.2 meters). Yorimitsu and the others caught it, pierced it with an iron skewer, and exposed it to a riverbed. Yorimitsu's illness left him immediately, and the sword that cut the spider was from then on called the Kumo-kiri (蜘蛛切り, spider-cutter).
The true identity of this tsuchigumo was said to be an onryō of the aforementioned local clan defeated by Emperor Jimmu.
This tale is also known from the very fifth noh, "Tsuchigumo." - source : wikipedia -

歌川国義 Utagawa Kuniyoshi

- quote - the sword Onimaru 鬼丸
Onimaru is one of the 'Tenka-goken', the five famous swords of Japan.
Its legend is about an ogre which made Hojyo Tokiyori, 5th regent in Kamakura era, suffer from nightmares. One night, he saw a dream of an old man, who turned out to be a spirit of the katana. After following the his advice in real world, the katana fell down and cut down the silver decoration of an ogre.
Since then, he never saw a nightmare again.
Imperial Household Agency is currently keeping this Onimaru. Unfortunately, it has only been displayed three times. - source : wasa-bi.com/topics -

Fujiwara no Chikata no Yonki 藤原千方の四鬼 The four demons of Fujiwara Chikata

- quote - Fujiwara no Chikata - kutsu 窟 cave (Takao, Iga City)
This is the castle of Fujiwara no Chikata, who appears in the Taiheiki, or Records of Great Peace.

In the Heian Period, noble family Fujiwara no Chikata started war with the imperial court, used the yonki (four devils: kinki 金鬼 gold devil, fuuki 風鬼 wind devil, suiki 水鬼 water devil,
ongyoki 隠形鬼 / 怨京鬼 stealth devil)
to distress the imperial armies.
The waka poem of Kinotomo, who had come to put down Fujiwara no Chikata, said “All things, whether grass or tree, are ruled by the Emperor,
and not even a devil can turn his back to the Emperor and live in this land”
to disperse the four devils and Fujiwara no Chikata was defeated. The four devils are said to have been the original archetype for ninja. The Chikata monument was built in 1760, and commemorates Fujiwara no Chikata and Wakamiya deities. - source : iganinja.jp/en/place/spo -

Once upon a time King Ashoka (阿育王 Aiku-O) from India asked a human demon to throw three rocks to 琵琶湖 lake Biwako in Japan.
This is the beginning of an island called Shiraishi 白石島 "white stone island".

沖の白石 Oki no Shiraishi - rocks in the middle of Lake Biwako
There are now four rocks, sticking out from about 80 meters below the water level.
Now a favorite resting place for birds, which turned the rocks white from bird droppings.

At the shrine 綿向神社 Watamuki Jinja there is an ema 絵馬 votive tablet of a half-naked woman, only clad in koshimaki 腰巻 waste wrapper, and an Oni with only a fundoshi 褌1丁 male underware doing a bout of 相撲 sumo wrestling.- If any one can locate this ema, please share ! -

- quote - Umamioka Watamuki Shrine at the foot of Mt. Watamuki in Hino Town, Shiga Prefecture, is a historic shrine founded in 545. The enshrined deities are Amenohonohi no Mikoto, Amenohinadori no Mikoto and Takemikumaushi no Mikoto.
It was originally founded at the top of Mt. Watamuki and was transferred to the present place in 796.
The spring festival of the shrine
"Hino Festival” held on May 2 to 4 every year is the most gorgeous festival on the eastern side of Lake Biwa. The festival dates back to 1170, since when ancient rituals and customs have been passed down to the present time.
On the main festival day on May 3,
a lot of Shinto rites are performed in traditional ways. The highlight is the parade with the 3 holy children and the guarding attendants in samurai costumes in the lead, who are followed by a sacred horse, shrine priests and the 3 mikoshi from the attached shrines and sumptuous 16 festival floats, which were donated by wealthy Omi merchants about 130 to 200 years ago. The festival is prefecturally designated as an intangible cultural property. - source : nipponkichi -

At the temple 明王院 Myo-O-In in the village of 葛川 Kuzugawa there is an ema 絵馬 votive tablet showing an aka-oni 赤鬼 red demon with white fundoshi ふんどし underpants and a waist wrapper made from 豹の毛皮 panther skin. His opponent is a huge man with strong muscles, all naked. They have a rope around the neck
kubihiki 首引き and pull in a contest of strength, a kind of "Neck tug of war".

ura kimon 裏鬼門 the back-side kimon deomn gate
The kitchen entry and main pillar of the home are the KIMON.Taking the opposite direction is the ura kimon.
There in the garden you should not plant anything, because that will cause bad luck.

Once upon a time at night, 赤鬼と青鬼 the red Oni and the blue Oni were doing a bout of Sumo near a cliff.
The red Oni fell down. When the villagers looked the next morning, there was a dead human.
This must have been the bad doing of a fox.

Once upon a time a husband went hunting at night. When he came back he found that his pregnant wife had been eaten by an 鬼婆 Onibaba Hag. But she had not eaten the baby in her belly. The child grew up to become a big, strong man. He went after the Onibaba, gave her iron bullets to eat and killed her. Finally he had taken revenge at the enemy of his mother !
They say he was the ancestor of Sumo wrestlers.
And the Onibaba turned out to be a dead fox.

This is maybe the first children's book where 鬼の娘 the daughter of an Oni is the hero. She was supposed to have her first meal of a human 「お食い初め」and the story tells about the ruses the human, a young man, who tries to survive. He has to win a neck tug of war with many Oni.
Text by 岩城範枝 / Illustrations by 井上洋介

At the 住吉神社 Sumiyoshi Shrine there is an ema 絵馬 votive tablet.
On the left side of the rope sits a strong man with a sword at his side, and a hachimaki 鉢巻 headband.
On the right side sits an Oni with protruding eyes.